Probably she did not at first distinguish Marya Timofyevna, of whose presence she had not been informed.

Stepan Trofimovitch was the first to notice her; he made a rapid movement, turned red, and for some reason proclaimed in a loud voice: "Darya Pavlovna!" so that all eyes turned on the new-comer.
"Oh, is this your Darya Pavlovna!" cried Marya Timofyevna.

"Well, Shatushka, your sister's not like you.

How can my fellow call such a charmer the serf-wench Dasha ?" Meanwhile Darya Pavlovna had gone up to Varvara Petrovna, but struck by Marya Timofyevna's exclamation she turned quickly and stopped just before her chair, looking at the imbecile with a long fixed gaze.
"Sit down, Dasha," Varvara Petrovna brought out with terrifying composure.

"Nearer, that's right.